I read in an answer to another question that you do not need religion for morality and that without religion it is not like you are going to be raping or murdering. So how does Islam change morality and what is the difference between an atheists morality and Islam’s? Do we need religion for morality? Morality without religion? In which way is the morality we have in Islam better than that of the morality of the atheists or other religions?
I don't know what answer exactly you are referring to, but I will assume you mean the accepted answer in the question you posted in the comments.
That answer is a classic case of circular reasoning. Basically, the argument goes: I don't follow a religion. I don't kill and rape meaning I am moral. Hence, I do not need religion to be moral.
The hidden assumption here is that killing and raping and harming other people is the only way to be immoral. That is the circular reasoning. First, you define what morality is, then claim that you are moral based on your own definition.
However, as Islam makes clear, killing and raping is not the only immoral thing. Zina (having extramarital affairs) is also, for instance, immoral. But, without a religion, some people do not think so and act on it. This is evident in many irreligious cultures.
The reason we need Islam to define morality is not to make people act on their own definitions of morality. People will do that anyway. Most people do think killing and raping is immoral. That is why they do not do it. But, that is a very low bar. There are more things than not killing and not raping in morality.
I am sure even the Nazis justified themselves with their morality.
But, the reason Islam is needed is to make people act moral even if they don't like it or don't think it is necessary. Because God tells people what is morality. They cannot decide for themselves.
Allah says in the Quran:
If they do not respond to you, you will know that they follow only their own desires. Who is further astray than the one who follows his own desires with no guidance from God? Truly God does not guide those who do wrong. (28:50)
There is a basic rule in logic, inverse of an if-then statement is false except for certain trivial cases please check this for crash tutorial. Pertaining to your question the logical relation reads as
(S) : if A is a believer, then A is moral.
The converse of this statement is
(C) : if A is moral, then A is a believer.
And the inverse is
(I) : if A is not a believer, then A is not moral.
Finally its contrapositive is
(CP) : if A is not moral, then A is not a believer.
If we accept (S) to be true, then only (CP) is always true. The others are usually false. The post you are referring to corresponds to (CP) and it is simply false logic. There is really not to much you can do about it.
From a worldly perspective, an unbeliever can be moral. However, morality, when relations between Allah (swt) and abd are considered, without acknowledging Him, abd cannot really be moral. Consider the fact that, Allah (swt) thought about us (you, me, all the readers of this post, etc.) before even our parents could imagine us. He gave us life, He gave us our parents as our full-time, zero-cost, slave-like guardians. Yes slave-like, consider a mom waking up in midnight to sooth her baby, and dad striving to put bread on table. The bounties that Allah (swt) grants to every individual is countless. Given this, how is it at all possible anyone who ignores his/her Creator to claim to be moral.
Islam teaches humanity wisdom, superior morals, best etiquette.
This is wishful thinking @"without religion it is not like you are going to be raping or murdering" - In some cultures is it seen as perfectly OK to engage in cannibalism (essentially murder) and in other cultures to kidnap women for forceful marriage (having sex with them without consent, essentially rape). These cultures are without God's guidance, having abandoned it long ago. So in contrary to the claim, it's exactly what we'd see and worse. They won't stop until Islam spreads to these areas and guides them away, as it spread to Arabia and stopped the practice of burying female infants.
Many of today's atheists are influenced by Abrahamic religious ideals, through which they learned civility as taught by God. Had these same people been born in these other areas of the world where cannibalism and kidnapping is seen as OK, they would not hold the same ideals and ethics.